KDP spine width and cover size, worked out

Spine width is page count times the thickness of one page of your paper. Read from kdp.amazon.com on 2026-10-20.

Thickness per page

A worked example

A 104-page book on white paper: 104 x 0.002252 in = 0.234 in of spine. With 0.125 in of bleed on each side, a 6 x 9 in book's full cover is 6 + 0.234 + 6 + 0.25 = 12.484 in wide and 9.25 in tall.

Text on the spine

"We only print spine text on books with more than 79 pages."
KDP, Paperback Submission Guidelines
"the cover will be rejected and require adjustment before your book can go live."
KDP, Create a Paperback Cover

"with at least 0.0625" (1.6 mm) of space between the text and the edge of the spine."
KDP, Paperback Submission Guidelines

In KDP's words

"If the file is sized at dimensions other than those expected, Print Previewer will note the discrepancy and prevent approval."
KDP, Fix Paperback and Hardcover Formatting Issues
"Cover Width = Bleed + Back Cover Width + Spine Width + Front Cover Width + Bleed"
KDP, Paperback Submission Guidelines
"Bleed at the bottom of the page cannot exceed 0.125" (3.2 mm)."
KDP, Paperback Submission Guidelines